This invention relates to measuring the electromagnetic (E/M) characteristics of soils, and, more particularly, to a trombone slotted line earth probe combination for measuring the E/M characteristics of soils.
One method of obtaining the propagation constant and other RF electrical characteristics of soil in a given area is to measure the electromagnetic (E/M) characteristics of the soil in that area. Such measurements will provide, among other characteristics, the propagation constant of the soil, since knowledge of the E/M impedance of the soil in a given area is tantamount to knowing the propagation constant of that soil. Prior to this invention, field measurements of the E/M characteristics of soil have generally been obtained by utilizing modified standard laboratory equipment for this field work. This modified laboratory equipment generally includes a standard slotted line, a tripod used to support a standard slotted line, a voltage standing wave ratio meter, rigid transmission line coupled between the slotted line, an in-situ earth probe and a VHF/UHF generator. While this combination of equipment provides satisfactory measurements, the mechanical procedures for setting up and taking down the equipment are very time consuming. These mechanical procedures take up to as much as 60% of the total "on site" time.
This invention provides apparatus for making field measurements of the E/M characteristics of soil that is readily set up and taken down. Very little of the "on site" time is spent to set up and take down the apparatus of this invention. Further, the apparatus is so designed that the detector probe is easily moved up and down along the line to measure the voltage standing wave ratio and first null.